i wanna get the evo3 16g for my wrx. however i know i don't need over 20 psi of boost and like the info says...

"Keep in mind that this turbo is NOT for low boost applications (14psi -18psi). This turbo is intended to be operated in the 18psi to 22psi range. If you want to run it at a lower boost pressure, please special order your turbo over the phone so that we can add a low pressure actuator and additional WG porting to your order. Please also note that in some cases with very large off-road catless exhaust systems it may not be possible to keep boost under 20psi, so if your car is "illegal" or "off-road" in that sense, select the optional WG porting for low boost operation."

i'd like close to 300whp and prob go with 650cc injectors and fuel pump of course. i know this turbo would get me there. so my question is what wastegate pressure spring should i get? also should i get the optional wastegate porting? and most importantly will this get me close to my goal? btw i have an hks catless DP. couldn't i just get a boost controller and turn the boost down or do i NEED a low pressure wastegate?

close to 300whp...but it'd be a aggressive tune with probably a close to 20psi boost level. I'd think. Could be wrong. But, I'd think if you want that number...let the higher boost level on it. Why don't you want to go up to 20 psi? I'd figure the 18-20 psi range would be right about where you'd want it.

so 20psi would be alright on a stock internal motor with no meth/water injection? i'm guessing that is about the limit with out some sort of cooling? i wouldn't mind boosting 18-20 i just figured i could hit my figure w/o that much boost.

Well, I'd hope you'd have the supporting mods. Like a bigger than stock 04 TMIC. A STI TMIC probably would be fine...but, I'm sure most people might say a larger than STI TMIC might help out more. Nevermind the other mods: larger injectors, fuel pump, TBE, and some sort of EM.

so 20psi would be alright on a stock internal motor with no meth/water injection? i'm guessing that is about the limit with out some sort of cooling? i wouldn't mind boosting 18-20 i just figured i could hit my figure w/o that much boost.

I run 20psi on 93 octane no problems.You gonna be disapointed if your that wrapped up in hitting a "magic" number.Said it time and time again,there are so many variables.Altitude,ambient temp,humidity,supporting mods,tune,dyno and other smaller things like boost controler and compression of the engine.Before and after numbers on the dyno are more important than just looking at the max #'s.

yea i have the full exhaust setup, and i did forget to mention about the intercooler situation, and i'd deffinitally get another setup. and dumdum i only meant roughly 300whp. that sounds like a good number its just kinda stupid to say i wanna hit 290. And i totally understand all of the variables and such but i think my mark is attainable. as of now i have a cobb stage two with up pipe and cobb intake (no cats) so thats abougt 220whp if i'm not mistaken. so with the added fuel and 4+- psi of boost, not to mention another 30% cfm over stock. that should be about where i'd end up???

It's not really the boost, it's the added flowrate of the larger turbo. You can make more power with a larger turbo at lower PSI than you can a smaller turbo at high PSI. There are lots and lots of other factors I'm leaving out but the point is don't equate boost to horsepower. They're not even close to related.